The present invention relates to a magnetic material, and more particularly to a magnetic alloy film suitable for use in high-density magnetic recording and reproduction, which is required in digital video tape recorders (VTR's) and high-resolution VTR's and to a magnetic head using such a film.
A material for a core of magnetic heads has been required not only to have a high saturation flux density (Bs) but also to excel in hardness, corrosion resistance and thermal stability for soft magnetic properties. Conventionally, the cores of magnetic heads have been made of ferrite, sendust and Co-based amorphous material among others. The Bs levels of these materials, however, are only about 5 kG for ferrite, 10 kG for sendust and 8 kG for Co-based amorphous material and, thus, a material with a higher Bs level has been further called for to realize stable performance of high-density magnetic recording and reproduction.
In this connection, there is a recent report on a favorable soft magnetic film made of an alloy having a composition of FeMC (M:/Zr, Ti, Hf, Ta, Nb), having a Bs level of about 16 kG (Technical Report of the Society of Telecommunications, MR89-12 (1989)). This FeMC-based film, however, involves such problems yet to be solved as (1) susceptibility to rust because of its much carbon content, (2) insufficient hardness and the resultant low wear-resistance and (3) inability to provide a satisfactory soft magnetic alloy film surpassing 17 kG in a Bs level.
With a view to solving these problems, there has been proposed in Japanese Patent Laid-Open Publication No. 54-229408 (229408/1989) a magnetic alloy film having the composition of FexMyNz, where M is at least one metal selected from a group of Zr, Nb, Hf, Ta, Mo and Ti, N is nitrogen, x, y, and z represent atomic percentages, EQU 65.ltoreq.x.ltoreq.94, 5.ltoreq.y.ltoreq.25, 3.ltoreq.z.ltoreq.20, and x+y+z=100.
Incidentally, the soft magnetic properties of the FexMyNz film is thermally stable in the range of about 550.degree. to 550.degree. C. Therefore, during glass deposition to process this film into a video head, the temperature cannot be raised beyond this range, leaving the glass still viscous and adversely affecting the product quality and yield. In order to achieve improvements in these respect, the thermal stability of the film should be further raised. In other words, a magnetic alloy film with greater thermal stability should be obtained.